/*
 *  Copyright (c) 2002 Sun Microsystems, Inc.  All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *
 *  1. Redistributions of source code must retain the above copyright
 *  notice, this list of conditions and the following disclaimer.
 *
 *  2. Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in
 *  the documentation and/or other materials provided with the
 *  distribution.
 *
 *  3. The end-user documentation included with the redistribution,
 *  if any, must include the following acknowledgment:
 *  "This product includes software developed by the
 *  Sun Microsystems, Inc. for Project JXTA."
 *  Alternately, this acknowledgment may appear in the software itself,
 *  if and wherever such third-party acknowledgments normally appear.
 *
 *  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and
 *  "Project JXTA" must not be used to endorse or promote products
 *  derived from this software without prior written permission.
 *  For written permission, please contact Project JXTA at
 *  http://www.jxta.org.
 *
 *  5. Products derived from this software may not be called "JXTA",
 *  nor may "JXTA" appear in their name, without prior written
 *  permission of Sun.
 *
 *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 *  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 *  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 *  DISCLAIMED.  IN NO EVENT SHALL SUN MICROSYSTEMS OR
 *  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 *  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 *  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 *  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 *  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 *  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 *  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 *  SUCH DAMAGE.
 *  ====================================================================
 *
 *  This software consists of voluntary contributions made by many
 *  individuals on behalf of Project JXTA.  For more
 *  information on Project JXTA, please see
 *  <http://www.jxta.org/>.
 *
 *  This license is based on the BSD license adopted by the Apache
 *  Foundation.
 *
 *  $Id: PeerViewRandomStrategy.java,v 1.1 2005/05/15 19:18:36 hamada Exp $
 */
package net.jxta.impl.rendezvous;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.SortedSet;

/**
 *  Random without replacement
 */
final class PeerViewRandomStrategy implements PeerViewStrategy {
    private transient List copy = new ArrayList();

    private transient SortedSet set;


    /**
     *  Constructor for the PeerViewRandomStrategy object
     *
     *@param  set  Description of the Parameter
     */
    PeerViewRandomStrategy(SortedSet set) {
        this.set = set;
        reset();
    }

    /**
     *  {@inheritDoc}
     *
     *@return    Description of the Return Value
     */
    public PeerViewElement next() {
        synchronized (set) {
            if (set.isEmpty()) {
                copy.clear();
                return null;
            }
            if (copy.isEmpty()) {
                reset();
            }
            PeerViewElement pve = (PeerViewElement) copy.remove(0);

            if (set.contains(pve)) {
                return pve;
            }
        }
        return next();
    }


    /**
     *  {@inheritDoc}
     */
    public void reset() {
        copy.clear();
        copy.addAll(set);
        Collections.shuffle(copy);
    }
}

